Yanshan Gao

This review critically evaluates amine-functionalized layered double hydroxides as a promising class of solid adsorbents specifically designed for DAC applications.

This review evaluates design strategies for copper-based bifunctional catalysts in coupled NH ₃ -SCR and CO oxidation. It clarifies structure–activity relations, reaction pathways, and deactivation mechanisms under industrial conditions.

This review provides a comprehensive framework spanning catalyst design, enhancement strategies, reactor engineering, and practical applications to bridge the gap toward industrial implementation.

A comprehensive review of recent advancements in hydrophobic modification strategies for zeolites is presented, aiming to enhance the adsorption of volatile organic compounds.

A bimetallic IrRu nanoparticle catalyst supported on oxygen-deficient WO ₃ is developed, leading to a significant enhancement in NO reduction efficiency and N ₂ selectivity under oxygen-rich conditions.

Emerging as a critical technology for atmospheric carbon dioxide (CO ₂ ) removal, the mass deployment of direct air capture (DAC) demands breakthrough innovations in efficient and stable adsorbent materials that simultaneously achieve high capacity, oxidative durability, and low cost. Herein, a hydroxyl‐rich Mg _0.55 Al layered double hydroxide (LDH) support is developed via aqueous miscible organic solvent treatment, circumventing energy‐intensive calcination while engineering mesopores for efficient polyethyleneimine (PEI) loading. The optimized 60 wt.% PEI modified Mg _0.55 Al‐CO ₃ AMO‐LDH achieves a CO ₂ uptake of 3.92 mmol g ⁻¹ under simulated wet air at 25 °C and retains 90.8% capacity over 20 cycles. Crucially, the abundant surface hydroxyls of uncalcined LDH, validated by ¹ H Nuclear Magnetic Resonance and in situ X‐ray Photoelectron Spectroscopy, form hydrogen bonds with PEI, suppressing oxidative degradation. After 3 h at 120 °C in simulated air, PEI‐LDH retains a CO ₂ capacity of 1.06 mmol g ⁻¹ , significantly outperforming PEI/mixed metal oxide and conventional silica‐based adsorbents. In situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy further reveals that hydroxyl‐mediated amine anchoring minimizes water co‐adsorption. This work establishes a dual strategy of hydroxyl preservation and mesopore engineering to design cost‐effective DAC adsorbents, achieving both high capacity and exceptional stability under realistic operating conditions.

Although supported solid amine adsorbents have attracted great attention for CO₂ capture, critical chemical deactivation problems including oxidative degradation and urea formation have severely restricted their practical applications for flue gas CO₂ capture. In this work, we reveal that the nature of surface hydroxyl groups (metal hydroxyl Al–OH and nonmetal hydroxyl Si–OH) plays a key role in the deactivation mechanisms. The polyethyleneimine (PEI) supported on Al–OH-containing substrates suffers from severe oxidative degradation during the CO₂ capture step due to the breakage of amine-support hydrogen bonding networks, but exhibits an excellent anti-urea formation feature by preventing dehydration of carbamate products under a pure CO₂ regeneration atmosphere. In contrast, PEI supported on Si–OH-containing substrates exhibits excellent anti-oxidative stability under simulated flue gas conditions by forming a robust hydrogen bonding protective network with Si–OH, but suffers from obvious urea formation during the pure CO₂ regeneration step. We also reveal that the urea formation problem for PEI-SBA-15 can be avoided by the incorporation of an OH-containing PEG additive. Based on the intrinsic understanding of degradation mechanisms, we successfully synthesized an adsorbent 40PEI-20PEG-SBA-15 that demonstrates outstanding stability and retention of a high CO₂ capacity of 2.45 mmol g⁻¹ over 1000 adsorption–desorption cycles, together with negligible capacity loss during aging in simulated flue gas (10% CO₂ + 5% O₂ + 3% H₂O) for one month at 60–70 °C. We believe this work makes great contribution to the advancement in the field of ultra-stable solid amine-based CO₂ capture materials.

A new concept named CO ₂ /NO _x storage and reduction (CNSR) is proposed for the first time for flue gas treatment.